Tag: engineered air nozzles

Henri Coanda was a Romanian aeronautical engineer best known for his work on the fluid dynamic principle with his namesake, the Coanda effect. Before this, Henri patented what he labeled as a jet engine.

Jet Engine

Henri’s patent (French patent No. 416,54, dated October 22, 1910) gives more information into how he envisioned the motor working. When air entered the front, it passed through different cavities that caused the air stream to first contract and then expand. In Henri’s opinion this contraction and expansion converted the air’s kinetic energy into potential energy. The air ultimately was channeled to a diffuser where it was discharged.

Henri stated that the efficiency of this engine could be improved by heating the air in the cavities, Henri’s logic was that this would increase the pressure of the air passing through.

What is obviously lacking in the patent (including identical ones taken out in England and the United States) is any mention of injecting fuel, which in a true jet engine would combust with the incoming air. Judging only by Henri’s patent, it was little more than a large ducted fan and it could not have flown. Throughout Henri’s career he changed his story many times on whether this plane actually flew or not.

Not to cast too much shade on Henri’s accomplishments he did discover the Coanda effect. The Coanda effect states that a fluid will adhere to the surface of a curved shape that it is flowing over. One might think that a stream of fluid would continue in a straight line as it flows over a surface, however the opposite is true. A moving stream of fluid will follow the curvature of the surface it is flowing over and not continue in a straight line. This effect is what causes an airplane wing to produce lift, and enhance lift when the ailerons are extended while at lower air speeds such as occurs during takeoff and landing.

Ailerons positioned for cruising speed

EXAIR uses the Coanda effect to offer you highly engineered, intelligent and very efficient compressed air products. Our designs take a small amount of compressed air and actually entrain the surrounding ambient air with the high velocity exiting compressed air stream to amplify the volume of air hitting a surface.

Surrounding Air Captured (Entrained) In Exiting Compressed Air Stream1). Compressed Air Inlet, 2). Compressed Air Exiting EXAIR Super Air Knife 3). Surrounding Air Being Entrained With Exiting Compressed Air StreamEXAIR Super Air Amplifier Entraiment

When you are looking for expert advice on safe, quiet and efficient point of use compressed air products give us a call. We would enjoy hearing from you.

A manufacturing plant EXAIR worked with made cast aluminum tubes for the automotive industry. After the parts were cast, a machining operation would clean the ends. This left coolant and metal shavings inside the tube. Before going to assembly, they had to clean the part. They created a two-tube fixture (reference picture above) to fit the 25mm tubes in place.

Two home-made nozzles were used to fit inside the tubes to blow compressed air. The nozzles were attached to the ends of two 17mm pipes which supplied the compressed air. A cylinder was used to push the nozzles from the top of the aluminum tube to the bottom then back up again. The liquid emulsion and debris would be pushed downward into a collection drum. When they started operating their system, the inside of the tubes still had contamination inside. They wanted to improve their process, so they looked for an expert in nozzle designs, EXAIR.

Back Blow Air Nozzle Family

EXAIR designed and manufactures a nozzle for just this type of operation, the Back Blow Air Nozzles. We offer three different sizes to fit inside a wide variety of diameters from ¼” (6.3mm) to 16” (406mm). They are designed to clean tubing, pipes, hoses, and channels. The 360o rear airflow pattern can “wipe” the entire internal surface from coolant, chips, and debris. For the application above, I recommended the model 1006SS Back Blow Air Nozzle. This 316SS robust design would fit inside the tubes above. The range for this Back Blow Air Nozzle is from 7/8” (22mm) to 4” (102mm) diameters. The customer did have to modify the function of the equipment by placing the cylinder and the rods under the aluminum tubes. The reverse airflow would still push the contamination into the collection drum that was placed underneath the tubes.

After installing the model 1006SS onto the rods, the cleaning operation became more efficient. Not only was the entire internal diameter getting clean, they were able to turn off the compressed air until they reached the top of the tube. With the model 1006SS, they only needed one pass to clean. This cut the air consumption in half, saving them much money by using less compressed air. In addition, they were able to speed up their operation by 20%. Cleaner tubes, less time, cost savings; they were happy that they contacted EXAIR for our expertise.

Reverse Air Flow

If you need to clean the inside of tubes, hoses, pipes, etc., EXAIR has the perfect nozzle for you, the Back Blow Air Nozzles. EXAIR can also offer these nozzles on our VariBlast, Soft Grip and Heavy Duty Air Guns for manual operations. They come with Chip Shields and extensions that can reach as far as 72” (1829mm). Or like the customer above, automate the system to get a great non-contact cleaning.

If you require any more details, you can contact an Application Engineer at EXAIR. We will be happy to help.

Everyone knows there’s oxygen in our air – if there wasn’t oxygen in the air you’re breathing right now, reading this blog would be the least of your concerns. Most people know that oxygen, in fact, makes up about 20% of the earth’s atmosphere at sea level, and that almost all the rest is nitrogen. There’s an impressive list of other gases in the air we breathe, but what’s more impressive (to me, anyway) is the technology behind the instrumentation needed to measure some of these values:

Reference: CRC Handbook of Chemistry and Physics, edited by David R. Lide, 1997.

We can consider, for practical purposes, that air is made up of five gases: nitrogen, oxygen, argon, carbon dioxide, and water vapor (more on that in a minute.) The other gases are so low in concentration that there is over 10 times as much carbon dioxide as all the others below it, combined.

About the water vapor: because it’s a variable, this table omits it, water vapor generally makes up 1-3% of atmospheric air, by volume, and can be as high as 5%. Which means that, even on a ‘dry’ day, it pushes argon out of the #3 slot.

There are numerous reasons why the volumetric concentrations of these gases are important. If oxygen level drops in the air we’re breathing, human activity is impaired. Exhaustion without physical exertion will occur at 12-15%. Your lips turn blue at 10%. Exposure to oxygen levels of 8% or below are fatal within minutes.

Likewise, too much of other gases can be bad. Carbon monoxide, for example, is a lethal poison. It’ll kill you at concentrations as low as 0.04%…about the normal amount of carbon dioxide in the atmosphere.

For the purposes of this blog, and how the makeup of our air is important to the function of EXAIR Intelligent Compressed Air Products, we’re going to stick with the top three: nitrogen, oxygen, and water vapor.

Any of our products are capable of discharging a fluid, but they’re specifically designed for use with compressed air – in basic grade school science terms, they convert the potential energy of air under compression into kinetic energy in such a way as to entrain a large amount of air from the surrounding environment. This is important to consider for a couple of reasons:

Anything that’s in your compressed air supply is going to get on the part you’re blowing off with that Super Air Nozzle, the material you’re conveying with that Line Vac, or the electronics you’re cooling with that Cabinet Cooler System. That includes water…which can condense from the water vapor at several points along the way from your compressor’s intake, through its filtration and drying systems, to the discharge from the product itself.

Sometimes, a user is interested in blowing a purge gas (commonly nitrogen or argon) – but unless it’s in a isolated environment (like a closed chamber) purged with the same gas, most of the developed flow will simply be room air.

Another consideration of air make up involves EXAIR Gen4 Static Eliminators. They work on the Corona discharge principle: a high voltage is applied to a sharp point, and any gas in the vicinity of that point is subject to ionization – loss or gain of electrons in their molecules’ outer valences, resulting in a charged particle. The charge is positive if they lose an electron, and negative if they gain one. Of the two gases that make up almost all of our air, oxygen has the lowest ionization energy in its outer valence, making it the easier of the two to ionize. You can certainly supply a Gen4 Static Eliminator with pure nitrogen if you wish, but the static dissipation rate may be hampered to a finite (although probably very small) degree.

There are a number of fascinating facts about jets…both the aircraft engines and the EXAIR Intelligent Compressed Air Products:

Because they don’t require dense air to engage spinning blades (like their propeller driven counterparts,) they can operate at much higher altitudes. (Jet aircraft engines only)

They provide a high thrust, directed airstream, which makes them great for part ejection, chip removal, and part drying. (EXAIR Air Jets only)

With few or no moving parts, they are extremely reliable, durable, and safe. (Both jet aircraft engines and EXAIR Air Jets)

They use the Coanda effect (a principle of fluidics whereby a fluid flow tends to attach itself to a nearby surface, and follow that surface regardless of the flow’s initial direction) to do what they do.

EXAIR Air Jets use this principle to generate a vacuum in their throat, pulling in a large amount of “free” air from the surround environment, making their use of compressed air very, very efficient.

Now, since I’m not a pilot, nor do I particularly like to fly, but I AM a fluid dynamics nerd, the rest of this blog will be about the Air Jets that EXAIR makes.

All of our Air Jet products operate on the same principle…using the Coanda effect (as described above) to generate a high volume air flow while minimizing compressed air consumption:

(1) Compressed air enters and is distributed through an annular ring, and directed towards the discharge via the Coanda effect.(2) This causes entrainment of surrounding air, both through the throat, and at the discharge.(3) The total developed flow has tremendous force and velocity, for a minimal consumption of valuable compressed air.(1) Compressed air enters and is distributed through an annular ring, and directed towards the discharge via the Coanda effect.
(2) This causes entrainment of surrounding air, both through the throat, and at the discharge.
(3) The total developed flow has tremendous force and velocity, for a minimal consumption of valuable compressed air.

Model 6013 High Velocity Air Jet is made of brass for economy and durability. The annular ring gap (see 1, above) is fixed by a 0.015″ thick shim. Performance can be modified by changing to a 0.006″ or 0.009″ thick shim, which come in the Model 6313 Shim Set.

Model 6019 Adjustable Air Jet is brass construction, and dimensionally identical to the Model 6103. Instead of a shim that sets the annular ring gap, though, it has a threaded plug, with a micrometer-style indicator, to “fine tune” the gap.

If you need to operate at a different pressure because you require less or more force or simply operate at a different line pressure, this formula will allow you to determine the volume of air being consumed by any device.

Lets first consider the volume of the 1100 Super Air Nozzle at a higher than published pressure. As shown in the formula and calculations it is simply the ratio of gauge pressure + atmospheric divided by the published pressure + atmospheric and then multiply the dividend by the published volume. So as we do the math we solve for 17.69 SCFM @ 105 PSIG from a device that was shown consume 14 SCFM @ 80 PSIG.

Now lets consider the volume at a lower than published pressure. As shown it is simply the ratio of gauge pressure + atmospheric divided by the published pressure + atmospheric and then multiply the dividend by the published volume. So as we do the math we solve for 11.04 SCFM @ 60 PSIG from a device that was shown to consume 14 SCFM @ 80 PSIG.

When you are looking for expert advice on safe, quiet and efficient point of use compressed air products give us a call. Experience the EXAIR difference first hand and receive the great customer service, products and attention you deserve! We would enjoy hearing from you.

The other day I received a call from the Corporate Director of a manufacturing company with multiple locations across the country. He had grown frustrated with the service and quality he was receiving from his current Air Gun & Nozzle supplier. He explained that he was unable to buy the individual components to make repairs to the air guns and described the overall quality as “disposable”.

I asked him for model air gun he had been purchasing so that I could make an accurate comparison and recommendation for the equivalent or better EXAIR offering. As I researched this competitive air gun I was surprised to find out that the specifications were vague at best. What I mean by that is EXAIR clearly publishes air consumption @ 80 PSI, force which is specified @ 12″ from the nozzle and the sound level in dBA @ 3′ from the nozzle.

The customer reported an average noise reduction of over 15 dBA which looks considerable, however it is a greater gain than the number would indicate. An increase of 10 dB is required before sound is perceived to be twice as loud, therefore EXAIR lowered the perceived sound by over 150%!

When you are looking for OSHA safe, quiet and efficient point of use compressed air products give us a call. Experience the EXAIR difference first hand and receive the great customer service, products and attention you deserve! We would enjoy hearing from you.

Think about it…compressed air is, by definition, gas under pressure: potential (stored) energy. This energy is intended to do work, like operation of pneumatic tools, actuation of pneumatic cylinders, debris removal with an air gun or blow off device, and (even though I haven’t done it in a while) my personal favorite:

High pressure compressed air is meticulously made, prepared, and stored to ensure the number of surfaces equals the number of dives.

Uncontrolled, unplanned, or accidental releases of stored energy (regardless of the source) are inherently dangerous, and great care must be taken to guard against such incidents. This is accomplished, primarily, in three areas:

*Operation. This might be the most prevalent, because it involves the greatest number of personnel (e.g., everyone) as well as the ways compressed air is used (e.g., all of them.) It’s also the area where the most involved people (the operators) have the most control:

Personal protection. Don’t even think about operating a compressed air device without eye protection. Ever. Hard stop. Also, if the operation involves flying debris, a full face shield, long sleeves, gloves, etc. might be called for. Hearing protection may be required as well…keep in mind, even if an engineered device (like any of EXAIR’s Intelligent Compressed Air Products) generates a relatively low sound level, the impingement noise of the air flow hitting the object can reach dangerous levels.

Personnel cleaning is prohibited. The risk of injury to the eyes, respiratory system, and other parts is just too great to rely on personal protective equipment that’s designed for use while discharging compressed air AWAY from the body. While this is expressly prohibited in certain situations, OSHA has long recognized it as good practice for all industries.

No horseplay. ’nuff said. Plenty of better ways to have fun at work.

*Design. This one usually has the advantage of being traceable to a small number of people, and is also the one that’s most likely to be documented. This is where it starts…if the system is designed to fail, it doesn’t matter how much care the operators take:

Supply lines, fittings, and hoses must be rated for use with compressed air, up to and exceeding the maximum discharge pressure of the air compressor.

This goes for any tools, blow off devices, components, etc., serviced by the air system. The only thing worse than a component failing is a component failing in your hand.

Shut off valves should be located as close as practical to point(s) of operation. This allows you to quickly secure the flow of compressed air to a failed component, hose, etc., and prevent further damage or risk of injury.

Hoses shouldn’t be run across the floor, where they can become a trip hazard or subject to damage from stepping on them. This is a surefire way to find out the value of shut off valves (see above.)

*Product specification. Or, more simply put, using the right tool for the job. A broader discussion could include efficiency and performance, but we’ll stay within the confines of safety for the purposes of this blog:

Be mindful of dead end pressure. Blow off devices, especially hand held ones like air guns, are oftentimes fitted with a simple open-end discharge. If this is pushed into a part of the body, the pressurized air can break the skin and cause an air embolism. This is a serious injury, and can be fatal if it reaches the heart, lungs, or brain.

This is a key consideration to OSHA Standard 1910.242(b), which limits the downstream pressure when compressed air is used for cleaning to 30psi.

EXAIR products are compliant with this Standard by design…there’s always a relief path for the air pressure; they can’t be dead ended.

Because the compressed air exits through a series of holes, recessed between a ring of fins, any attempt to block the air flow will simply send it in another direction.

Harmful sound levels are a consideration as well. As stated above, hearing protection is required in many cases, but sound levels can be mitigated through the use of engineered products. EXAIR Intelligent Compressed Air Products, as a result of their high entrainment, generate a boundary layer of air flow that leads to dramatically lower sound levels than a similar-sized open end blow off device.

If you’d like to explore ways to make your compressed air system safer, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
Visit us on the Web
Follow me on Twitter
Like us on Facebook